Brake



1932. F. w. SAMPSON ET AL 1,336,594

BRAKE Filed March 8, 1929 2 Sheets-Sheet INVENTORJ fume/0r M mrmw BYJava 1/. 779775/Q ATTORNEY.

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vdrums and shoes such Patented Nov. 8, 1932 UNITED STATESPAQTENT oFFIcEFREDERICK w. SAMPSON, OF DETROIT, MICHIGAN, AND JOHN W. TATTER, OFCHICAGO, ILLINOIS; SAID SAMPSON ASSIGNOR TO CONTINENTAL MOTORSCORPORATION, OF

DETROIT, MICHIGAN, A CORPORATION OF LEWIS DIFFERENTIAL COMPANY, OFILLINOIS VIRGINIA, AND SAID TATTE-R ASSIGNOR TO CHICAGO, ILLINOIS, ACORPORATION OF BRAKE Application filed larch s, 1929. Serial a...345,298.

This invention relates to brakes and refers more particularly to fluidbrakes such as are used in connection with motor vehicles.

It is; an object of our invention to provide an improved brake mechanismwhich we have conveniently arranged in an assembly structure referred toas the master cylinder.

A further object of our invention resides in the provision of a cylinderand piston structure which serves both as a pressure applying means forthe brake system and also as a take-up for compensating for loss offluid in the system, brake band wear, and like facinvention thusprovides a compact structure sim lified in manufacture and use.

A further in the provision of means associated with the take-up devicewhereby it is impossible for the operator to take;up the brakesexcessively. This feature automatically assures the proper clearance forthe brake shoe and drum and provides a fool proof means for setting therake system for eflicientoperation;

A still further feature of the invention that additional fluid should.be placed in the system and also which is perhaps more important havingthe effect of quickly taking up any unusual clearance between the brakecessively heating the drums as in applying the brakes while the vehicleis going down a ing means for initially filling the system with fluid orsubsequently draining-the system.

Other objects of our invention reside in the novel combination andarrangement of parts more particularly hereinafter described andclaimed.

Referring to the drawings in which we ea-ture of this invention resideswhich acts 'on the piston of as is occasioned by exhave illustrated oneour invention,

Fig. 1 is a diagrammatic plan view of a motor vehicle chassis having ourbrake apparatus applied thereto,

- ig. 2 is a sectional elevation the master cylinder,

ig. 3 isa sectional view through 3-3 of i v Fig. 4 is a furthersectional elevation view thrlg'ugh the master cylinder at right anglesto ig. 2, I v Figs. 5 and 6 are diagrammatic views showing successivepositions of the pressure finger cams, and

preferred embodiment of view through Fig. 7 is a diagrammatic view ofone of the wheel brake devices. y

In the drawings reference character A represents the mastercylinderstructure compris- 'ing a casing 10 forming a fluid reservoir 11.

he casing 10 cooperates with the casinglO to provide. a cylinder12'within which is located a piston-structure B. Piston B has a head 13and skirt 14 guided by the walls of cylinder 12 and between the head andskirt is fixed a cup 15 of suitable resilient material such as rubbercomposition whereby thecylirider working space '16 is sealed againstcommunication with the reservoir 11 past the piston B. Thus the cylinder12 has a diameter larger than that of the cylinder of easing h by anamount suflicient to accommodate t e on cup 15 is shown fixed by a nut17 engaging the stem 18 of the piston head 13, the outer flange 19 ofcup.15 being clamped between the casings 10 and 10; The piston skirt 14carries a pin 20 engaging slot 21 in casing 10 whereby the piston mayreciprocate but is prevented from rotating.

, J ournaled by casing 10 is a rock shaft 22 having bearing engagingportions 23, 24, a suitable pedal 25 and arm 26 being connected torock'the shaft 22 for reciprocating piston B. Shaft22 has-avyoke portionproviding pressure fingers 27 which work in the annular space rovided bthe spaced flanges 28, 29 of the co lar' 30. T iscollar receives anadjust- 15, the latter substantially filling the I space etween piston Band cylinder 12. The

a 32, the lower end as rod 31 being for rod 31 is slotted at 33 ceivethe threaded shank 36 member 37, the latter having openings 38 toreceive the ends of pin 32. The openings -5 and 6) forme so as -len h ofthe pressure of t e piston stroke and thereby accelerating end of toreceive a screw driver and rod 31 is rotatably supported on the easingcover 34 by reason of the groove and spring clip 35 whereby rod 31 mayrotate but not reciprocate.

The stem 18 is ed to receive the pin. The upper internally threaded toreof the connecting 38 have a cam face 39 and vertical face 39, thepurpose of which will be later apparent. The member 37 is externallyknurled or grooved at 40 for engagement with spring 41 the latterexerting a drag on member 37 yieldingly re- Sisting its rotation.

The pressure fingers 27 preferably terminate in cam en aging surfaces 42(see Figs. to increase the leverage fingers toward the end the movementof the piston with respect to the pressure fingers. Thuseach cam surface42 has the two points 43 and 44, the point 43 engaging fiange 29 for thegreater part of the movement of pedal 25. Toward the end of the stroke,however, the point 44 becomes the point of contact with flange 29 thusincreasing the length of the pressure finger leverage by thedistancebetween points 43 and 44 and increasing the rate of travel ofthe flange 29 and piston B with respect to movement of pedal 25. A sprin45 restores the pedal 25 and piston B to bra e releasing position, asuitable stop 46 limiting the return movement. I

The master cylinder A also preferably has provision for removing airfrom the brake stem and filling with the brake fluid which is preferablya liquid, or for removing the liquid from the system. Thus assuming themaster cylinder to be used in connection with a vehicle braking systemas diagrammatically illustrated in Fig. 1 in which chassis C has rearwheels 47 and front wheels 48, with fluid brake devices of suitableconstruction associated in the well known manner with the wheels as atD. Thus in Fig. 7 we'have illustrated one of the brake devices D inconventional manner as comprising drum 58 fixed to its wheel, this drumbeing engaged by shoe 59 carrying friction lining 60, the hose 51conducting fluid under pressure for acting on cylinder 52 to spread thebrake shoe 59 into engagement with drum 58. Clearance 61 is maintainedby springs 62 supplemented by any inherent resilience of shoe 59 wherebyon release of the pressure'in hose 51 the shoe will clear the drum ascustomary. From cylinder chamber 16 the fluid under pressure is passedthrough outlet 49, 50 and connecting hose or tubes 51 to the variousbrake devices D. A passage 52 communicates at a suitable point with thefluid system, this passage having-an associated valve 53 threaded: 1yengeging the enlar ed opening 54. ThlS valve as a plurality 0 ionitudinal ports or passages 55 (see Figs. 2 an 3) whereby when the valveis unseated fluid may pass longitudinally of the valve. is slotted at 56for engagement with a screw driver to open or close the valve.Theenlarged passage 54 opens u wardly into an ad ditional passage 57whic opens into chamber 11, the passa e 57 being internally threaded toaccommo ate asuitable suction apparatus or suction pump (not shown)which may be of any suitable type.

The operation of our improved apparatus is as follows, assuming themaster cylinder to be associated with a vehicle brake system asillustrated. To fill the system the cover 34 is removed and valve 53 isunseated and a suction device connected to the threaded passage 57. Thesuction will remove substantially all of the air throughout the entiresystem including chamber 16, pipes 51, and brake devices D. Whensubstantially all of the air has been removed the fluid reservoir 11 isfilled with the brake liquid and then the. suction device isdisconnected from passage 57 whereupon the liquid will automaticallyfill the entire system. Our system does not require a perfect vacuumprior to filling with the brake liquid as the presence of a smallquantity of air in the system is not objectionable in actual practice.The valve 53 is then seated and the cover 34 replaced, the mastercylinder being then ready for operation.

In applying the brake devices D the operator presses pedal 25 torockshaft 22 and move pressure fingers 27 downwardly against flange 29.During this operation collar 30, pin 32, member 37 and piston B movedown- .wardly as a unit exerting a pressure on the fluid in chamber 16and throughout the system. Should excessive lost motion develop in thesystem such as might be occasioned by brake lining wear, loss of fluid,or like factors then it is desirable to take up this lost motion. Thisis accomplished by turning rod 31 clockwise in Fig. 3. During theinitial movement of rod 31 rotaton of the connecting member 37 will beprevented due to the drag exerted thereon by spring 41. However pin 32will be rotated with rod 31, the ends of the pin engaging cam face 39whereby the connecting member 37 and piston B will be moved downwardlyuntil pin 31 reaches the face 39 (see Fig. 4) at which time and uponfurther rotation of rod 31 the connecting member 37 will rotate with rod31. Since piston B is fixed against rotation by pin 20, the piston Bwill be moved downwardly by engagement of the threaded shank 36. Whenresistance then the operator is advised that all lost motion is taken ufrom the system and in the present embodiment the usual brake shoes 59The end of valve 53 to rotation of rod 31 is encountered desiredclearance. This is particularly im-' 7 will be in engagement with thedrums 58 of the brake devices D. The operator then releases the rod 31whereupon the pressure in the fluid in some instances supplemented bythe sprin s 62 and any inherent spring of the usual bra e shoes willtend to move piston B upwardly. It is of course desirable to provideclearance 61 between the brake shoes 59 and drums 58 and the amountofthis clearance is always automatically provided in our device, thisclearance corresponding to the downward travel of piston B while pin 32travels along groove face 39. The piston B is thus moved thispredetermined amount before effecting any relative adjustment between iston B on one hand and connecting mem er 37 and pedal 25'0n the otherhand. Thus the operator cannot, in taking-up slack or in adjusting thebrakes at the master cylinder, set the fluid pressure so high that onrelease of rod 31 the brake shoes 59 will not have their portant whenthe adjustment is made by one inexperienced with the general brakesystem which includes the average driver of an automobile. Thus when rod31 is released after making adjustment, piston B will be forcedupwardly, rod 31 and collar 30 being rotated,

reversely by groove face 39 to restore the parts to the position of Fig.4. If the parts should not fully restore as aforesaid then on operationof brake pedal 25 the parts will be forced-into the restored position.We.have therefore provided a take up device which has a predeterminedinitial movement corresponding generally to dis lacement of suflicientfluid to take up bra e shoe clearance, followed by a secondary movementeffective to take up lost motion in the system, the initial movementbeing automatically restored on completion of the take up adjustment.

What we claim as our invention is 1. In a fluid brake system, a mastercylinder structure, a piston, a brake device, fluid pressuretransmitting means intermediate the master cylinder structure and brakedevice, said master cylinder structure having a fluid reservoir, aconduit intermediate the reservoir and pressure transmitting means, avalve in said conduit and within the master cylinder structure, andmeans associated with said conduit and adapted for connection with asuction producing device whereby the system may be drained of fluids.

2. A master cylinder for fluid brake systems comprising an upper casingformed with a cylinder and fluid reservoir, a lower casing having acylinder coaxial with the upper cylinder and of greater diameter,.a

piston operable within said cylinders and having an upwardly extendingskirt contacting with the walls of the upper cylinder, said pistonhaving a head contacting with the walls of the lower cylinder, ayielding sealing element clamped between the piston and its head andalso between the up r and lower 3. A master cylinder for brakesystemscomprising a casing structure formed with a portion having acylinder, a piston fitted within said cylinder and extending beyond saidcylinder, said casing structure formed with a second portion, meanssecuring said casing portions together, said second casing portionprovided with a second cylinder co \axial with the first said cylinderand havin a greater diameter than said first cylinder, said pistonextending intofsaid second cylinder and spaced therewithin, and aflexible sealing element intermediate said second cylinder and saidpiston and filling the space therebetween.

4. A master cylinder for brake systems comprising a casing structureformed with areservoir portion and a. cylinder, a piston fitted within.said cylinder and extending beyond said cylinder, said casing structureformed with a second portion, means securhaving a greater diameter thansaid first cylinder, said piston extending-into said second cylinder andspaced therewithin, and a sealing element adapted to stretch on pistonmovement intermediate said second cylinder and said piston, said sealingelement substantially fillin the space intermediate the piston and saidsecond cylinder.

5. A master cylinder for brake systems comprising a casing'structureformed with a portion having a cylinder, a piston fitted within saidcylinder and extending beyond said cylinder,- said casing structureformed with a second portion, means securing said casing portionstogether, said second casing portion provided with a second cylindercoaxial with the first said cylinder and having a greater diameter thansaid first cylinder, said piston extending into said second cylinder andspaced therewithin, and a sealing element intermediate said secondcylinder and said piston adapted to stretch on piston movement, saidsealing element substantially filling the space intermediate the pistonand said second cylinder, one end of said sealing element being clampedbetween said casing portions.

comprising a casing structure formed with a portion having a cylinder, apiston fitted within said cylinder and extending beyond said cylinder,said casing structure formed with a. second portion, means securing saidcasing portions together, said second casing portion provided with asecond cylinder co- 6. A master cylinder for brake systems axial withthe first said cylindera'nd having a greater diameter than said firstcylinder, said piston extending into said second cylinder and spacedtherewithin, a flexible sealing element intermediate said secondcylinder and said piston adapted to stretch on piston movement, saidsealing element substantially filling the space intermediate the pistonand said second cylinder, one end of said sealing element being clampedbetween said casing portions, and a piston head member secured to the.piston and having engagement with the walls of said second cylinder.

7 A gmaster cylinder for brake systems comprising a casing structureformed with a portion having a cylinder, a piston fitted within-saidcylinder and extending beyond said cylinder, said casing structureformed with a 'second portion, means securing said casing portionstogether, said second casing portion provided with a secondcylindercoaxial with the first said cylinder and having a greater diameter thansaid first cylinder, said piston extending into said second cylinder andspaced therewithin, a flexible sealing element intermediate said secondcylinder and said piston adapted to stretch on piston movement, saidsealing element substantially filling the space intermediate the pistonand said second cylinder, one end of said sealing element being clampedbetween said casing portions, and a piston head member fitted forengagement with the walls of said second cylinder, the other end of saidsealing element being clamped between the piston and said piston headmember.

8. A master cylinder for brake systems comprising a casing structureformed with a portion having a cylinder, a iston fitted within saidcylinder and extenfng beyond spectively provided with coaxial cylindersone of greater diameter than the other, a piston structure slidablyengaging the walls of one of said cylinders and extending into theother, and a flexible sealing element intermediate the piston and saidcylinder of greater diameter and adapted to stretch on piston saidcylinder, said casing structure formed with a second portion, meanssecuring said casing portions together, said second casing portionprovided with a second cylinder 00- axial with the first said cylinderand having a greater diameter than said first cylinder, said pistonextending into said second cylinder and spacedtherewithin, a flexiblesealing element intermediate said second cylinder and said pistonadapted to stretch on piston movement, and a piston head member fittedto the piston and having engagement with the walls of said secondcylinder.

9. A master cylinder for brake systems comprising cooperating casingstructures respectively provided with coaxial cylinders one of greaterdiameter than the other, a piston structure slidably engaging the wallsof one of said cylinders and extending into the other and a sealingelement filling the space between the piston and the cylinder of greaterdiameter and adapted to stretchon piston movement. a

10. ,A master cylinder for brake systems comprising cooperating casingstructures me

